324 



COMPARATIVE ANATOMY. 



A curious fold of the skin of the abdomen is present to a greater or less degree 

 in Marsupials and in Echidna. This pouch or marsupium serves to protect 

 the young, which are born in a very unripe condition, and thus renders possible 



Otl 



Of 



V. 



IMI;. 2f)3. -YAUiors JMIUMS OF UTERI. A, B, ( ', 1), diagrams showing the 

 dilfeivjit stages in the fusion of the Miillerian ducts: A, uterus bicornis ; B, 

 nliTus sinijilrx ; (', uterus duplex ; D, uterus bipartitus. E, female urinogenital 

 :i]i|>;ivatus of J///.s7,'//W, with embryos (*, *) in the uterus. F, ditto of Hedgehog 

 ( Erinaceus). 



Od, Fallopian tube ; Ut, uterus ; J r i/, vagina ; Ce, cervix uteri ; Ot, abdominal aper- 

 tmv nf l'';i]]n]ii:in tube ; t, t, accessory si-xual glands ; ?, rectum; Xi<g, uriiio- 

 .t,'enita] sinus ; N, kidney ; A*//, adrenal ; Ur, ureter; B, urinary bladder. 



;i l.ni'ji !((, n ncct inn lid \vccn 11 ic niolln-r and embryo during lactation. Theaper- 

 tuiv of tin- marsupial pouch opens anteriorly or posteriorly, according to the 

 11 mdc of life of (lie animal, and is provided with a muscle capable of closing it. 



